This is an application for a five-year competing continuation of Princeton University's institutional Ruth L. Kirschstein National Research Service Award (NRSA) training program in population. The training objectives of Princeton's graduate program in demography are to provide interdisciplinary instruction with a firm base in the social sciences and strong training in the technical aspects of demographic and statistical methods for careers in demographic research and teaching. This training is accomplished through formal coursework, one-on-one mentoring and advising, and involvement in the research projects of the training faculty. Of particular note are the expanded course offerings in health. In this application we request funds for six predoctoral trainees and two postdoctoral trainees annually for the period of 5/1/2006 - 4/30/2011. The 26 members of the training faculty at the Office of Population Research mentor students in research characterized by five signature themes: (1) health and wellbeing, (2) migration and development, (3) children and families, (4) social inequality, and (5) data/methods. NRSA funds provide invaluable financial aid for training the next generation of American demographers, who will dedicate their careers to teaching population studies in both developed and developing countries, and who will reshape the contours of the field through their own research programs. The funds from this training grant permit the program in demography to expand beyond the small number of students who could be supported through individual departments and to attract the best students in the field. The research of trainees both during and after their graduate studies is broadly aimed at improving public heath and wellbeing. Examples include evaluating the efficacy of interventions to reduce the risk of HIV, estimating the cost-effectiveness of contraception among teens, examining minority representation in the military, exploring the pathways between socio-economic status and health, examining how residential segregation has shaped the epidemiology of TB among minority populations, evaluating the social and biological linkages to health among the elderly, examining how financial incentives affect union formation, exploring the determinants of resilience of children of teenage mothers, understanding the deterioration in health behaviors among second-generation Hispanics, and evaluating the lessons learned from yellow rain for chemical and biological weapons investigations.